Water repellent and foldable, so that it can also just cover your children’s legs. this is a favourite way to ride though the winter (and summer for that matter…) wrap the kids up warm, fold the box cover over their knees (pop a hot water bottle in too ?) and avoid the bulk of a rain tent and the sail effect…keep the seat dry when they are not in it, also hides your shopping when you leave it parked up..a fav optional extra…